To prune or not to prune, and how much

Even though I am a book lover and avid reader, my favorite classes in school always involved a hands-on lab or field study.  Sometimes it was learning how to identify or key plants while traipsing though a field of native wildflowers or cultivated specimens on the OSU campus.  Next it would be getting my hands dirty studying about soils.  I even tried to burn down my chemistry lab once!  It always made more sense once I had actually done what I was learning about.  One of my favorite instructors taught landscape maintenance and I loved to prune.  Still do.  There is something about directing growth, changing shape and just sort of tidying things up a bit.  This is coming from a woman that has the messiest desk this side of Einstein and can’t make a decision about what to throw out in her home.  But I love to prune!  My husband jokes that his job in our garden is to follow behind me and pick up after me.  When I prune, I start at one end of the garden and work my way around to the other end, leaving a trail of trimmings.  I’m pretty much fearless as well.  Okay, maybe that’s not entirely true.  I know the basic concepts and I am willing to experiment.  And for the most part, I’m not afraid to cut something back drastically if I think it needs it and it will regrow.

Every once and  a while, I do get intimidated.  That happened with the laceleaf Japanese Maple that had grown quite large in my front yard.  They are exquisite trees and this specimen had done especially well.  I was fearful that I would destroy its shape or somehow ruin the plant.  I had the gumption to ask my friend, and former dean of horticulture at OSU, Bud Weiser to help me prune my Japanese Maple.  On an unseasonably warm May day, he appeared at my house and proceeded to share his technique for pruning.  Bud has years of experience sculpting bonsai, creating other forms of art and he had just taught a class at the nursery on pruning Japanese Maples.  I knew I was in good hands!  I truly learned something that day.  Bud’s technique does not involve pruners and he was very drastic in the amount of growth that he removed.  The maple was about a third or a quarter of its original size when my husband returned from work.  I wanted to train it taller as well and that was accomplished with a brace.  I think my husband referred to it as a ponytail.  At any rate, by the next spring it was as large as it had been originally.  The tree really benefitted.  The main, sculptural branches had been established.  And I was not afraid to tackle it’s pruning again.  I was able to maintain the pleasant structure.  Notice I have not shared with you Bud’s actual pruning technique.  It is not because it is a secret, but rather because Bud will be sharing that technique during our Pruning 101 class on Sunday, September 25th at 1 pm.  Garland Nursery’s gardening expert, Karen Hopson is leading the class.  She is a wealth of knowledge and a wonderful speaker.  Bud is a perfect compliment to her.  This class is a low key, extremely informational class that will help to empower you to tackle your pruning projects with confidence.  This is a popular class.  There are already 55 people signed up.  There’s still space.  Just give us a call at 541-753-6601.  It’s free, too!

Now I will share a few pruning basics that always come in handy.  In simple terms, most flowering plants produce their flowers either on growth from the previous year or from the current year.  Many Hydrangeas are an example of plants that flower on last year’s growth.  So if you go through and cut them completely back in the winter time, you will lose or delay the flowers for the next season.  Contrast that with Butterfly Bush which bloom on new growth and bloom better if they are cut back severely in the winter.  Fortunately, there are many online references to tell you which plants are which.  The A-Z Plant Dictionary is a great library reference.  But a great rule of thumb for pruning flowering plants is to do so immediately after they flower.  You really can’t go wrong if you do that.

Another generalization that, while not true for every plant in the category, is very useful is to not severely prune needled evergreens (or conifers).  Most needled evergreens will not regrow if they are cut back beyond 3 years of growth.  Most keep 3 years worth of green growth and have no foliage beyond that.  Cutting into branches without foliage causes a stump rather than a beautiful regrowth like might occur with a plant like English Laurel.  So if you really want to keep a conifer from outgrowing its space, it’s best to prune a little each year.  This is another plant group that benefits from the use of hands rather than pruners to shear growth.  To keep the plant more compact, break the new growth in half in the spring as it elongates but before the needles open up.  If you are beyond that stage, then perhaps it could be turned into a sculptured plant.  At the very least, this is a good time to use a technique that I enjoy, which is to gently move aside the portion you are thinking about pruning off to see what the plant will look like without it.  Often, if you are pruning out branches underneath other branches, you may not even notice the loss if the upper branch completely covers the cut.

Other basic helpful info.  When pruning, cut above an outward facing growth bud.  The bud that is below the cut is generally the one that will dominate growth.  If it faces inward, the growth will go inward.  It is healthier for the plant if the growth goes outward.  Sometimes we are not worried about that, say for example with hedges.  A general shearing works great for hedges.  A pruning cut should be just above a bud and angle downward.  Any portion of branch above the cut will die, so leaving only a small area is better.  Don’t cut so close that you risk damaging the growth bud, however.  A downward angle to the cut allows water to drain off, preventing rot.

I am probably in need of taking a remedial pruning class myself.  There are often changes in gardening recommendations based on scientific study.  There may be some new or revised tips that I don’t know about.  All the more reason to check out our class on Sunday.  Hmmm…maybe I’ll have to sit in on it.

About Brenda Powell

I'm one of the owners of a family-owned retail nursery. I have a degree in horticulture from Oregon State University. I love to garden and read. My technically savvy but horticulturally challenged husband, Mitch, spends most of his time as slave labor in the garden. Thank goodness he adores me! My goal in this blog is to share my enjoyment of gardening, my love of nature, and my addiction to books. Did I mention I like to cook, too?
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